Apparatus for producing artificial fog



Nov. 1, 1960 R. J. G. BURGELL 2,958,666

APPARATUS FOR PRODUCING ARTIFICIAL FOG Filed NOV. 20, 1957 4 Sheets-Sheet Roy J G. BURGELL Invenlor A ttorn e ys Nov. 1, 1960 R. J. G. BURGELL 2,958,666

APPARATUS FOR PRODUCING ARTIFICIAL FOG Filed Nov. 20, 1957 4 Sheets-Sheet 2 5 Roy J G. BURGELL Inventor Mimi, By W flui A ltorneys Nov. 1, 1960 R. J. G. BURGELL 2,958,666

APPARATUS FOR PRODUCING ARTIFICIAL FOG Filed NOV. 20, 1957 4 Sheets-Sheet 3 II l X Rev J G BURGELL Inventor A ttorneys Nov. 1, 1960 R. J. G. BURGELL 2,958,666

APPARATUS FOR PRODUCING ARTIFICIAL FOG Filed Nov. 20, 1957 4 Sheets-Sheet 4 \IIIIIIIIIIIIIIIIIIIII&

ROY J. G. BURGELL Inventor Attorneys Patented Nov. 1, 1960 APPARATUS FOR PRODUCING ARTIFICIAL FOG Roy J. G. Burgell, Orchard, Cape Province, Union of South Africa, assignor to Orchard Development Company (Proprietary) Limited, Orchard, Cape Province, Union of South Africa, a Union of South Africa corn- P y Filed Nov. 20, 1957, Scr. No. 697,685

Claims priority, application Union of South Africa Nov. .20, 1956 13 Claims. (Cl. 252-359) This invention relates to animproved method and apparatus for the generation of an artificial fog, smoke screen or like dispersion in air used to prevent or minimise damage by frost in orchards, vineyards and the like and for insecticidal purposes.

Apparatus is known whereby an artificial fog, smoke screen or the like is produced by the introduction into the exhaust manifold or other region or area of the exhaust system of an internal combustion engine, of a suitable heat-vaporisable liquid fuel or other vaporisable substance with or without the simultaneous introduction of water, in such a manner that said fuel or the like and water (if included) is vaporised and converted into smoke or fog and is projected from the exhaust conduit of the said internal combustion engine along with the exhaust gases.

In introducing the fuel or other fogor smoke-producing substance, its point or region of introduction into the exhaust system of the engine, must be so chosen that at this point or region the required heat is generated (by the normal operation of the engine) to effect the required vaporisation to form the fog or smoke screen, as the case may be. Preferably the introduction takes place at or adjacent to the hottest region of the exhaust conduit or manifold of an internal combustion engine, which is preferably the engine of a vehicle such as a motor lorry, tractor or the like on which the apparatus may be mounted. If the feed is too great complete vaporisation does not take place, while if it is insufiicient the fuel oil or the like is carbonised.

The said fuel or other smoke-producing material is preferably introduced by means of jet orifices incorporated in the exhaust manifold of the engineso as to direct a stream of the vaporisable fuel or the like on the one hand, and water (if included) on the other hand on to a focal point or area such as the usual hot spot of the exhaust system of the engine. Both fuel and water are preferably fed to these orifices or jets at a pressure of approximately 15 to lbs. per square inch which pressure is preferably obtained by air from a suitable pump or the like and is applied to the containers for these liquids. The flow of the fog or smoke, as the case may be, and the particle size thereof, is controlled by means of manually operated metering valves mounted conveniently on the dashboard of the vehicle.

It has, however, been found that the efficiency of this known method as regards its smokeor fog-producing capabilities and the particle size of the smoke or fog produced, depends on the size and kind of the internal combustion engine used, on the properties of the injected fuel, on the load and speed of the engine and especially on the control of fuel injection as also on the atmospheric conditions prevailing at the time. It, therefore, follows that to obtain the best results in any particular engine, the amount of fuel injected has to be limited by the jet size to match the engine and the load thereon. In addition, the feed pressure has to be kept constant and controlled and a certain temperature in the exhaust manifold of the engine must be reached before the injection of the smokeproducing material commences, and such temperature, or a higher temperature, must be maintained during the operation of the device.

In this connection it will be understood that the introduction of the fog-producing liquid has a cooling effect in the exhaust manifold proportional to the rate at which it is introduced. In addition, the condition of working of the engine has to be fixed in regard to the load and speed and the fogging device has to be adjusted to this condition. Furthermore, arrangements must be made whereby the means controlling the supply of the fog-producing substance is closed or made inoperative when no feed pressure is present to avoid exhaust gas penetrating the device. It has accordingly been found that special control means should be provided to regulate the injection of the fog-producing liquid or the like, according to the heat generated at that point or region of the exhaust manifold or system to which the said fog-producing liquid or the like is introduced.

Broadly, therefore, the present invention consists in the provision of a control unit comprising a valve adapted to regulate the supply of fog-producing material such as an oil fuel to the engine exhaust manifold or system, which valve is arranged to be controlled for opening and closing purposes through the medium of a heat-sensitive device, the moving parts of which are arranged to be actuated in accordance with variations in the temperature at said point or region above a minimum value. A preferred fogor smoke-producing substance is diesel fuel oil and hereinafter this term will be used to define the fog-producing substance without, however, limiting the invention to the use of this particular liquid.

According to a preferred arrangement of the control unit, the air pressure applied to a fuel oil supply container, is used in conjunction with the above-referred to heatsensitive device, to control the flow of fuel oil to the engine manifold or system. The heat-activated portion of the heat-sensitive device is preferably incorporated in a tubular tail piece or the equivalent adapted to be fitted to or fixed on to the end or other portion of the usual exhaust pipe of an internal combustion engine, whereby the temperature of the exhaust gases containing the fog or smoke, is employed to actuate the heat-sensitive device. These temperatures although lower, for all practical purposes vary proportionately to the temperatures existing at the same time at the point or region of introduction of the heat-vapourisable liquid or the like, whereby these exhaust temperature variations can be used to control the rate of introduction of the heat-vapourisable liquid by suitable calibration of the heat sensitive device.

According to this preferred arrangement, the valve (hereinafter referred to as the fuel valve), controlling the supply of fuel oil or the like to the engine exhaust manifold, is actuated for opening and closing purposes through the medium of a flexible diaphragm to which it is connected, or by which it is constituted, said diaphragm forming a partition between two chambers, one of which, termed the lower chamber, is connected to the oil fuel in the supply container, while the other, termed the upper chamber, is in communication with the pressure air as supplied to the said supply container, and with an air control valve, which when open reduces the air pressure in the upper chamber to permit opening of said fuel valve. The said fuel valve is biassed towards its closed position by spring means. A moving part of the heat-sensitive device is connected or associated with the aforesaid air control valve and the arrangement is such that when the exhaust manifold is cold or insufliciently heated to cause vaporisation of the fuel .oil for fog-producing purposes, the said air control valve remains closed and the pressure on each side of the said diaphragm is thereby kept equal, whereby the fuel control valve remains in its closed position by reason of the action of its spring. When, however, the exhaust manifold has been heated to a suflicient extent to cause vaporisation, the heat-sensitive device operates to open the said air control valve, thereby releasing the air pressure on the upper side of the flexible diaphragrn, whereby the fuel pressure in the lower chamber causes the said fuel valve to open against its spring-biassed means, so that fuel oil is supplied to the exhaust manifold in the engine. It is to be understood that the extent of opening of the fuel control valve varies according to the extent to which the heat-sensitive device operates to open the said air control valve releasing the air pressure in the upper chamber of the valve casing, and consequently is dependent on the temperature of the exhaust gases containing the fog or smoke produced.

It will be understood from the above explanation that, since the air pressure and the fuel pressure are equal, at times when the exhaust manifold has not yet reached a sufficiently high temperature to cause vaporisation, the diaphragm is in balance, but due to the action of the spring-biassing means of the fuel valve, it is held in its closed position. A further feature is that if no air pressure is applied to the supply container for the oil fuel, the fuel valve remains closed and fuel oil will, therefore, not pass into the engine manifold when it is cold and, therefore, inoperative.

In a preferred arrangement of the invention, the aforesaid control unit is conveniently attached to the fuel oil supply container and suitable pipes or tubes are led off therefrom to the pressure air supply and to the oil fuel supply to the exhaust manifold of the en ginen Preferably the end of the or each such fuel oil supply pipe or tube is fitted to a suitably calibrated jet nozzle, which projects into the exhaust manifold of the engine in the required position to inject the fuel oil into that portion of the exhaust manifold which will be heated sufficiently to create efiicient vaporisation of the fuel oil. Under certain conditions of working, such calibrated jet nozzle may be made adjustable such as making it in the form of a needle control valve.

The moving part of the heat-sensitive device operating the air control valve is adjustably connected to or associated with it through lever means, whereby adjustment can he made of the time when oil fuel injection commences in relation to the temperature of the exhaust gases.

Preferably, the heat-sensitive device employs a Bourdon tube as its main moving part while the said air control valve, controlling the release of air pressure may be a two-way valve arranged so that in one extreme position full air pressure is applied to the flexible diaphragm, while in the other extreme position greatly reduced air pressure is applied thereto which, of course, results in the fuel oil valve being opened to its fullest extent. Preferably, however, the air control valve is simply a spring-pressed flap valve coacting with the end of a small bore conduit communicating with the upper chamber associated with the diaphragm. The tubular device for fitting to the end of the exhaust pipe is in the form of a muffler the interior of which is provided with the heat exchange portion of the heat-sensitive device such as a tubular coil filled with a suitable liquid or gas for transmitting pressure to the Bourdon tube part of the heat sensitive device.

A pressure gauge is connected to the air pressure line to the air control valve and a second pressure gauge is connected to the air line to the fuel container. The first mentioned pressure gauge is for indicating the variations in pressure as the air control valve is operated by the heat-sensitive device and will thereby give a measure of the operation of the fuel valve.

To enable the invention to be more clearly understood and carried into practice, reference is now made passage 16 connected to the feed pipe '4.

to the accompanying drawings in which like references denote like parts throughout the several views.

In the drawings:

Fig. l is a diagrammatic View showing the general layout of the apparatus as applied to an internal-combustion engine;

Fig. 2 is a front elevation of the fuel container of Fig. 1;

Fig. 3 is an end sectional view of the fuel container of Fig. 2;

Fig. 4 is a diagrammatic part-sectional view illustrating generally the operation of the control unit;

Fig. 5 is an enlarged fragmentary front elevation of the operative parts of the heat sensitive device;

Fig. 6 is an under plan view of Fig. 5 with the addition of the pointers, front glass and control knob;

Fig. 7 is a part-cut-away front elevation of the heat sensitive device;

Fig. 8 is a plan view of the fuel valve unit with connections;

Fig. 9 is a part-sectional view of the heat-sensitive device of Fig. 8;

Fig. 10 is a part-sectional elevation taken on line XX of Fig. 8;

Fig. 11 is a sectional elevation taken on line.XIXI of Fig. 8 and showing the connecting means of the heatsensitive device to the fuel valve unit; and

Fig. l2 is a sectional view taken on line XII- -XH of Fig. 8.

Referring to Figs. 1 to 3 of the drawings, reference 1 denotes the exhaust manifold of an internal-combustion engine 2 such as that driving a truck on which the apparatus of the invention is carried. The smokeor fog-producing substance such as fuel oil is carried in the closed cylindrical container 3 whence it is delivered by the pipe 4 to the exhaust manifold 1.

The fuel oil or the like is caused to be delivered by way of a fuel valve unit 5 to the exhaust manifold 1 by the application of air under pressure to the fuel oil container 3, by way of the pipe 6, obtained from an air pump or other convenient source (not shown). The opening and closing of a diaphragm valve in the valve unit 5 is controlled by way of a heat-sensitive device 7 connected to a tail piece comprising a heat exchange coil device 8 by a conduit 10, which device is adapted to be attached to the end of the exhaust pipe 9 from the exhaust manifold 1. The heat-sensitive device is so calibrated that no fuel oil or the like from the container 3 will be delivered to the exhaust manifold 1 until the temperature of the exhaust gases have reached a value high enough to ensure that the fuel oil or the like introduced into the exhaust manifold 1, will then be vaporised by the heat thereof. If the temperature drops below this minimum value, the said valve will close. Air pressure gauges 11 and 12 are connected to the fuel valve unit 5 so that gauge 11 indicates the air pressure in the container 3 and gauge 12 indicates the air pressure which exists between the aforesaid diaphragm valve and an air control valve incorporated in and actuated by the heat-sensitive device 7 and forming an integral part of the mechanism thereof.

A fuel outlet pipe 13 provided with a strainer and located by a guard ring 14, leads from the lowest point in the container 3 to the fuel valve unit 5 as shown in Fig. 3.

Reference is now made to Fig. 4 which shows diagrammatically the arrangement and operation of the various parts of the apparatus. In this figure reference 15 denotes a flexible diaphragm constituting the fuel Valve proper which is spring-pressed towards its closed position with respect to the open end of a fuel outlet Air under pressure from the pipe 6 is led to the space above the fuel in the container 3 and to the space 17 above the diaphragm 15, This space 17 is connected by small bore pipe 18 to the inside 'of the heat-sensitive device 7 which is actuated by the Bourdon tube 19 which in turn is operated by the heat exchange coil device 8. The end of the pipe 18 is arranged to be closed by a spring biassed air control valve 20, mounted on one end of a pivoted valve lever 21, the pivot axis of which is adjustable to a limited extent by being mounted on a pivoted bar 22 controlled by the manually adjustable eccentric stop 23.

In operation, if air pressure is applied to the device via the pipe 6 when the engine is stationary, or if running, before the minimum temperature previously referred to has been reached, such air pressure will act equally on both sides of the diaphragm fuel valve 15, but owing to the extra pressure supplied by the spring 24, the fuel valve will remain closed. The valve will of course also be closed at this stage. As the engine warms up and the temperature of the exhaust gases rises sufliciently to actuate the Bourdon tube 19, its movable end attached to a link 25 rises until a stop pin 26 on the link 25 makes contact with the underside of the valve lever 21, and by tripping it, opens the valve 20. The result of this is that the pressure in the chamber 17 falls sufficiently for the fuel valve 15 to be raised against the action of spring 24 as a result of the air pressure in the container 3, so that the outlet passage 16 is opened to permit fuel to be forced up the outlet pipe 13, through the outlet passage 16 and pipe 4 to the exhaust manifold 1, where it is vaporised and discharged as a stream of smoke or fog particles from the exhaust pipe 9.

The eccentric stop 23 is to provide means for manually adjusting the position of the valve lever 21 relatively to the stop pin 26 whereby means are provided for varying the time when the fuel valve 15 will open as regards the heat generated in the exhaust manifold 1 and the consequent temperature of the exhaust gases passing in contact with the heat exchange coil device 8. This provision enables accurate control to be exercised over the particle size of the smoke or fog being produced, which control under certain working conditions can be critical.

Reference is now made to Figs. 5, 6, 7 and 9, which illustrate in detail the construction of the heat-sensitive device 7, and Figs. 8, 10, 11 and 12 which illustrate in detail the construction of the fuel valve unit 5. As shown in Fig. 2, the heat-sensitive device 7 is, for convenience, mounted on top of the fuel valve unit 5.

The heat-sensitive device 7 is basically a pressure gauge using the well known Bourdon tube principle and employing the movement of the free end of the tube to cause operation of valve means controlling the admission of fuel oil or the like to the exhaust manifold 1. As clearly shown in Figs. 7 and 9, the heat-sensitive device is in the form of a gauge provided with a face plate 30 and a glass front 31, forming the front of a cylindrical casing 32 fixed to a base 33 by means of which it is attached to the fuel valve unit 5 by studs passing through the holes 34.

Referring now to Figs. 5 and 6, reference 35 denotes the main substantially T-shaped frame member which is fixed adjacent to the bottom of the casing 32 and carries the operating mechanism of the device. This mechanism comprises the pivoted bar 22 mounted on the pivot pin 36 extending from the main frame member 35 to a front frame part 37. The bar 22 carries a terminal tube part 38 to which the end portion of the tube 18, which is of flexible material such as rubber, is attached. The valve 20 on the valve lever 21 co -acts with the extreme end of the tube part 38 and is normally held in its closed position by the leaf spring 39 fixed to the bar 22 :and bearing against the underside of the inner end of the valve lever 21 as clearly shown. The bar 22 is bent downwardly at its free end and there carries the pivot pin 40 of the valve lever 21.

The pivoted bar 22 is biassed by the spring 41 upwardly against the eccentric stop 23 which is arranged to be rotated by the external knob 42 via the spindle 43 to which the knob 42 is keyed by the grub screw 44. The link 25 is attached by the stop pin 26 to a locating arm 45 pivotally mounted on the pin 36, which arm 45 is provided with a plurality of holes 46 for adjusting the point of attachment of the link 25 thereto.

Rotatably mounted on the spindle 43 by means of a sleeve 47 is a disc member 48 which is capable of being partly rotated by the actuating lever 49 pivotally mounted on a pin 50 so that its inner end can engage with the crank pin 51 on the disc member 48, while its opposite end rests against a stop pin 52 projecting from the link 25. A heat-indicating pointer 53 is attached to the sleeve 47 and is biassed towards its zero position by the action of the tension spring 54.

Operation of the mechanism is as follows:

As soon as the free end of the Bourdon tube 19 commences to rise, stop pin 52 causes the actuating lever 49 to pivot so that its inner end coasting with the crank pin 51, imparts rotary motion to the disc 48 and through the sleeve 47 to the indicating pointer 53 which then commences to move over its scale 56 (see Fig. 7) against the action of the spring 54.

As the temperature of the exhaust gases increases the stop pin 26 in time makes contact with the underside of the outer arm of the valve lever 21 and thereby causes the valve 20 to uncover the end of the terminal tube part 38, as a result of which fuel oil from the container 3 is caused to be injected into the exhaust manifold 1 by way of outlet pipe 13, connection 57 to space 58 below the diaphragm fuel valve 15 (see Fig. 11), through the outlet passage 16 and the delivery pipe 4.

Referring to Figs. 8, 10, 11 and 12, it must be ex plained that air supply pipe 6 (see Fig. 4) is coupled to connection 60 whence the air enters the top portion of the container 3 (to which the valve unit 5 is attached in an air-tight manner), by way of the passage 61. Air pressure for holding the diaphragm fuel valve 15 in its closed position, enters the top chamber 17 by way of passage 59, a small metering aperture 62 in a fitting 63, up through the passage 64 and along the passage 65. The fitting 63 comprises an outer casing part adapted to be screwed into the edge of the unit 5. Located within this casing part is a thirnble-like part 66 having the metering aperture 62 in its front end. A clearing needle 67 attached to a push pin 68 projects through the metering aperture 62 and is arranged to be operated against the pressure of the spring 69 when required for clearing the metering aperture 62 in case of blockage. A suitable diameter for the metering aperture is 0.45 millimeter and for the clearing need-1e a diameter of 0.35 millimeter is suitable. The object of choosing such small dimensions is to reduce to a minimum the loss of pressure air which takes place when the air release valve 20 is open and the apparatus is operating.

The top chamber 17 communicates with the terminal tube part 38 (see Fig. 5) by way of a connection 76 (see Figs. 9 and 11), which by projecting through the base 33 of the heat-sensitive device is capable of being a push air-tight fit in a rubber insert '71 when the two parts are assembled.

Referring to Figs. 4, 8 and 12, the usual spigot of the air pressure gauge 11 is adapted to be screwed into the fitting 72 which communicates by Way of passages '73 and 74 with the interior space of the container 3, while air pressure gauge 12 is similarly adapted to be connected to the fitting 75, which communicates by Way of passages 76, 77 and 78 with the top chamber 17.

Referring to .Figs. 5, 6, 7 and 9, it will be noted that the knob 42 is rotatably mounted in an aperture in the front glass 31 by being secured to a collared sleeve 80 by the grub screw 81 which sleeve 80 has a hand or pointer 82 attached to its inner collared end which is arranged to be swung over the upper scale 83 on the face plate 30. This scale is provided for the purpose of determining the particle size of the fog or smoke being produced. Since the spindle 43 is keyed to the eccentric stop 23, rotation of the knob 42, rotates it. The setting of the pointer 82 on its scale 83 accordingly indicates the angular position of the eccentric stop 23 with respect to the pivotally mounted bar 22., which in turn determines the time of opening of the air valve 20 in relation to stop pin 26 actuated by movement of the Bourdon tube 19. If the air valve 20 is allowed to open early, a coarse particle size will be produced, whereas if the air valve 20 is allowed to open late, a fine particle size will result. This means that with the pointer 82 set on the left-hand side of scale 83, a coarse particle size will result while if set on the right-hand side, a fine particle size will result. The intermediate portion of scale 83 will give particle sizes varying between very coarse and very fine whereas adjustment of the setting of the pointer 82 will give any desired particle size within the possible range of the apparatus.

The function of the eccentric stop 23 and thus of the control knob 42, may therefore be said to be that of determining the temperature at which a flow of fuel of the equivalent is fed to the jet or jets in the exhaust manifold 1 is maintained. Since the temperature of the exhaust gases drops when a feed is on and rises when it it cut off, due to the heat absorbed in vapourising the fuel, this method of control, based as it is on the temperature of the vapour issuing from the exhaust pipe, is extremely accurate. Since the feed heat relationship is that which primarily controls the particle size of the ultimate fog, it follows that if this relationship is acourately controlled, in a way which compensates for varying external atmospheric and ambient conditions, the fog particle size can likewise be accurately controlled.

This accurate control of particle size is of special importance when the fog produced by the apparatus is to be used for insecticidal purposes.

It has been proved by experiment that in the treatment of certain insect pests, a particle size which is too large will have no appreciable affect on the insect, whereas a smaller particle size will have the desired lethal effect. For instance, when treating cockroaches it has been found that to knock out the adults the particle size required is from 60 to 100 microns, i.e. a wet fog, whereas to kill the younger and smaller cockroaches, a particle size of 20 to 30 microns is required, which is in fact a relatively dry fog. A further point is that the smaller particle size in a fog gives a greater volume of fog for the amount of fuel or the like used. Again a coarser particle size gives a faster fall-out than a fine particle size. An increase in temperature has the eifect of decreasing the particle size.

An important feature of the invention is that the control unit measures the temperature at the region of condensation of the vapourised fuel, i.e. at the stage when the vapour is in the form of a fog and in its most effective form. As regards the question of the heat governing the particle size, it was found that with an evaporation of 15 gallons per hour of a special petroleum distillate, the smallest particle size was 1 micron and the largest 25 microns, giving an average of 9. When the volume of the liquid was increased to 30 gallons per hour, i.e. under the same conditions, the smallest particle size was 2 microns and the largest was 80 microns, giving an average of 25 to 30 microns. For penetration effect such as in cracks, behind skirting boards and such like interstitial spaces, a small particle size is more effective than a large particle size.

'It has been found by experiment that insecticidal fogs or thermal aerosols are best produced by the use of certain petroleum distillates having high aromatic values in which the insecticide is soluble.

A suitable oil is that sold by the Standard Oil Company under their trade name of Sovacide D.Y. Various well-known insecticides such as DDT, B.H.C., Chlordane and Toxa-phene may be used withthis oil as the fogor aerosol-producing liquid.

What I claim is:

1. in an apparatus for producing an artificial fog, more particularly for agricultural and pest control purposes, by the introduction into the exhaust manifold region of the exhaust system of an internal-combustion engine, of a suitable-vaporisable fog-producing liquid from a liquid supply container and in such a manner that said liquid is vaporised and converted into a fog which is projected from the exhaust conduit of said internalcombustion engine along with the exhaust gases; the provision of mechanical control means for accurately regulating the injection of the fog-producing liquid according to the temperature at that region of the exhaust manifold into which the said fog-producing liquid is introduced, which control means comprises a control unit comprising a valve for accurately metering the supply of said fog-producing liquid to the engine exhaust manifold, means for supplying air pressure to the supply container for said liquid and to said valve, and a heat sensitive device connected to said valve for releasing air therefrom for controlling the opening and closing of said valve, said heat sensitive device having moving parts which are actuated in accordance with variations in the temperature at the said region of introduction above a minimum value.

2. Control means as claimed in claim 1, in which the control unit is attached to the fog producing liquid supply container and said control means further comprises a pipe extending from said valve to the exhaust manifold of the engine, and the end of the fog producing liquid supply pipe has fitted thereon a calibrated jet nozzle projecting into the exhaust manifold of the engine in a position for injecting the fog producing liquid into the portion of the exhaust manifold which will be heated sufiiciently to create efficient vaporisation of the fog producing liquid.

3. Control means as claimed in claim 1, wherein the heat-sensitive device comprises a heat-activated portion and a tubular tailpiece adapted to be fitted to the usual exhaust pipe of the internal combustion engine in which the heat-activated portion is mounted, whereby the varying temperatures of the exhaust gases containing the fog are employed to actuate the heat-sensitive device.

4. Control means as claimed in claim 3, wherein the heat-activated portion of the heat-sensitive device comprises a tubular coil having a suitable fluid therein for transmitting pressure, one of the moving parts of said heat sensitive device further comprising a Bourdon tube to which said coil is connected.

5. In an apparatus for producing an artificial fog, more particularly for agricultural and pest control purposes by the introduction into the exhaust manifold region of the exhaust system of an internal combustion engine, of a suitable heat-vaporisable fog-producing liquid from a liquid supply container and in such a manner that said liquid is vaporlsed and converted into a fog which is projected from the exhaust conduit of said internal combustion engine along with the exhaust gases; the provision of mechanical control means for accurately regulating the injection of the fog-producing liquid according to the temperature at that region of the exhaust manifold to which the said fog-producing liquid is introduced, which control means comprises a control unit comprising a valve for accurately metering the supply of said fog-producing liquid to the engine exhaust manifold, said valve having a space therein and a flexible diaphragm forming a valve-member and partitioning said space into two chambers, an upper chamber and a lower chamber, the lower chamber being connected to the fog producing liquid in the supply container, means for supplying air under pressure to the upper chamber 'of the valve and to the supply container, an air control valve connected to said upper chamber for reducing the air pressure in the upper chamber, spring means biassing said diaphragm towards its closed position, reducing the air pressure in the upper chamber permitting said diaphragm to open the said valve, a heat-sensitive device having a heat-sensitive element in the exhaust system and connected to the said air control valve for opening said air control valve when the exhaust temperature rises above a predetermined minimum, the extent of opening of the air control valve varying according to the extent to which the heat-sensitive device operates, whereby when the exhaust manifold is insufiiciently heated to cause vaporisation of the fog producing liquid for fogproducing purposes, the air control valve remains closed and pressure on each side of the flexible diaphragm is thereby kept equal and the liquid control valve remains in its closed position by reason of the action of its spring, and when said exhaust manifold has been heated to a suflicient extent to cause vaporisation, the heat-sensitive device operates to open the said air control valve, thereby releasing the air pressure on the upper side of the flexible diaphragm and the liquid pressure in the lower chamber causes said diaphragm, constituting the liquid valve, to open against its spring so that fog producing liquid is supplied to the exhaust manifold of the engine, the amount being dependent on the temperature of the exhaust gases containing the fog produced.

6. Control means as claimed in claim 5, wherein said heat-sensitive device has a moving part for operating the air control valve, and an adjustable lever means connected between said moving part and said air control valve, whereby adjustment can be made of the time when fog producing liquid injection commences in relation to the temperature of the exhaust gases.

7. Control means as claimed in claim 5, wherein said valve has between said air supply means and said upper chamber a small bore metering aperture, whereby the loss of pressure air when the air control valve is open, is reduced to a minimum, said control means further comprising a clearing needle positioned to project through said metering aperture, a spring-urged push pin to which said needle is attached, whereby said aperture can be cleared from the exterior of the apparatus.

8. Control means as claimed in claim 5, wherein the air control valve is incorporated in and forms an internal part of the mechanism of the heat-sensitive device.

9. Control means as claimed in claim 6, wherein the moving part of said heat-sensitive device is a Bourdon tube, and said air control valve is a spring-pressed flap valve, said valve having a small bore conduit communicating with the upper chamber the end of which is covered by said flap valve.

10. Control means as claimed in claim 9, in which said adjustable lever means comprises an intermediately pivoted valve lever on one end of which said air con trol valve is mounted, a stop member connected to the movable end of the opposite free end of said lever being in the path of said stop member, whereby movement of said end to a predetermined extent will cause the stop member to trip the valve lever and thereby to open the air control valve.

11. Control means as claimed in claim 10, in which said adjustable lever means further comprises a bar on the free end of which said valve lever is pivotally mounted the other end of said bar being pivotally mounted on said control means, means for adjusting said bar to vary the position of the free end of the valve lever with respect to the path of movement of said coacting stop member, whereby variation of the time of injection of the fog producing liquid is made possible, the means for adjusting the position of the said bar comprising an eccentric stop on said control means spring holding said bar against said stop, a spindle on which said eccentric stop is fixedly mounted, and an external knob on said spindle for rotating said eccentric stop for adjustment purposes, and spring means pressing the air control valve towards its closed position.

12. Control means as claimed in claim 11, wherein said stop means comprises a stop lever pivotally mounted on said control means, a stop adjustably mounted on the free end of said stop lever to which the end of said Bourdon tube is pivoted.

13. Control means as claimed in claim 11 and a disc member rotatably mounted on the spindle of the eccentric stop and a pointer on said disc and a scale with which said pointer cooperates on the device, a second stop pin on said stop member, a pivoted actuating lever projecting into the path of said second stop pin and a crank pin projecting from the disc member with which the other end of said pivoted actuating member engages, whereby said disc member and the pointer connected to it, are rotated in accordance with movements of the movable end of the Bourdon tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,997 Collins July 28, 1936 2,392,883 Roselund Jan. 15, 1946 2,402,402 Hickman June 18, 1946 2,426,846 Roselund Sept. 2, 1947 2,428,580 Pennow Oct. 7, 1947 2,432,372 Besler Dec. 4, 1947 2,451,019 Davis Oct. 12, 1948 2,607,743 Hession Aug. 19, 1952 2,630,412 Besler Mar. 3, 1953 2,686,160 Kell Aug. 10, 1954 

1. IN AN APPARATUS FOR PRODUCING AN ARTIFICIAL FOG, MORE PARTICULARLY FOR AGRICULTURAL AND PEST CONTROL PURPOSES, BY THE INTRODUCTION INTO THE EXHAUST MANIFOLD REGION OF THE EXHAUST SYSTEM OF AN INTERNAL-COMBUSTION ENGINE, OF A SUITABLE-VAPORISABLE FOG-PRODUCING LIQUID FROM A LIQUID SUPPLY CONTAINER AND IN SUCH A MANNER THAT SAID LIQUID IS VAPORISED AND CONVERTED INTO A FOG WHICH IS PROJECTED FROM THE EXHAUST CONDUIT OF SAID INTERNALCOMBUSTION ENGINE ALONG WITH THE EXHAUST GASES, THE PROVISION OF MECHANICAL CONTROL MEANS FOR ACCURATELY REGULATING THE INJECTION OF THE FOG-PRODUCING LIQUID ACCORDING TO THE TEMPERATURE AT THAT REGION OF THE EXHAUST MANIFOLD INTO WHICH THE SAID FOG-PRODUCING LIQUID IS INTRODUCES, WHICH CONTROL MEANS COMPRISES A CONTROL UNIT COMPRISING A VALVE FOR ACCURATELY METERING THE SUPPLY OF SAID FOG-PRODUCING LIQUID TO THE ENGINE EXHAUST MANIFOLD, MEANS FOR SUPPLYING AIR PRESSURE TO THE SUPPLY CONTAINER FOR SAID LIQUID AND TO SAID VALVE, AND A HEAT SENSITIVE DEVICE CONNECTED TO SAID VALVE FOR RELEASING AIR THEREFROM FOR CONTROLLING THE OPENING AND CLOSING OF SAID VALVE, SAID HEAT SENSITIVE DEVICE HAVING MOVING PARTS WHICH ARE ACTUATED IN ACCORDANCE WITH VARIATIONS IN THE TEMPERATURE AT THE SAID REGION OF INTRODUCTION ABOVE A MINIMUM VALUE. 